FlarePath

What happened

NTSB summary, verbatim

On January 25, 2013, at approximately 0457 mountain standard time, FedEx Express flight 1420, a Boeing MD-11F, N618FE, experienced a tail strike during landing on runway 17 at Denver International Airport (KDEN), Denver, Colorado. There were no injuries to the 3 flight crew, and the airplane sustained substantial damages. The flight was operating under 14 CFR Part 121 as a regularly scheduled passenger flight from Memphis International Airport (KMEM), Memphis, Tennessee, to Denver, Colorado. According to the flightcrew and a review of dispatch records, during the preflight while in Memphis, after receiving multiple weight and balance (W&B) messages, the captain had erroneously entered an airplane zero fuel weight (ZFW) that was 100,000 lbs. less than the actual ZFW when the first officer was out of the cockpit. After the captain made the incorrect ZFW entry, the flight crew did not perform another takeoff performance data briefing, and therefore did not recognize the captain's entry error that resulted in incorrect landing speeds calculated by the flight management software for the flight. During the approach, the flight crew did not notice indications that the target landing airspeed was too low, such as the Angle of Attack (AOA) indicator in the captains Heads Up Display (HUD) that was outside of the speed reference band, and the pitch of the airplane, which was about 7-8 degrees airplane nose up, whereas the normal airplane pitch on approach was 4-6 degrees pitch. The first officer also stated that during the approach he noticed that his airspeed indication had an amber box surrounding it, which is an indication that the airspeed had reached Vmin and was approaching a stall condition. During the flare and landing, the tail of the airplane struck the surface of the runway. The aircraft taxied normally to the cargo ramp, and an inspection revealed substantial damage to the skin, stringers, beams, APU compartment bulkhead, and aft pressure bulkhead of the airplane.

Photographs

1the aircraft, and what the investigators found

The aircraft before the accident

Probable cause

the Board's determination

the flight crews failure to perform a takeoff performance data briefing following the final entries into the Flight Management System, which would have alerted them to the incorrect weight entry and resulting incorrect landing speeds. Contributing to the accident was the failure of the flight crew to recognize and respond to various visual cues indicating the airplane's airspeed was too slow, resulting in a higher than normal pitch during landing and the tail of the airplane striking the runway.

Occurrence sequence

1 stepsNTSB coding · CICTT taxonomy

1 · Landing-flare/touchdown
Tailstrike
defining event

Findings

2 causal · 1 contributing

CAUSE
Personnel issues › Action/decision › Action › Forgotten action/omission — Flight crew
CAUSE
Personnel issues › Action/decision › Info processing/decision › Identification/recognition — Flight crew
FACTOR
Personnel issues › Action/decision › Action › Incorrect action performance — Pilot

Sequence of events

4 timed eventsfrom the FDR factual report · claude-fable-5-1 (in-session)

02:45:00 MSTtakeoffp.3
Start of plotted flight data (figures 1-6 cover the flight to the end of the recording at 05:03:18 MST); takeoff figures cover 02:47:00 to 02:50:00 MST
04:55:00-04:58:10 MSTlandingp.3
Landing period covered by the expanded-scale figures 7-12
04:56:51 MSTlandingp.3
During landing the vertical acceleration spiked at a maximum of 2.32 g; pitch angle increased to a maximum of 13.4 degrees nose up; computed airspeed approximately 122.5 knots (tail strike)
05:03:18 MSTtaxip.3
End of recording after a normal taxi to the cargo ramp

NTSB analysis

from the final report

On January 25, 2013, at approximately 0457 mountain standard time, FedEx Express flight 1420, a Boeing MD-11F, N618FE, experienced a tail strike during landing on runway 17 at Denver International Airport (KDEN), Denver, Colorado. There were no injuries to the 3 flight crew, and the airplane sustained substantial damages. The flight was operating under 14 CFR Part 121 as a regularly scheduled passenger flight from Memphis International Airport (KMEM), Memphis, Tennessee, to Denver, Colorado. According to the flightcrew and a review of dispatch records, during the preflight while in Memphis, after receiving multiple weight and balance (W&B) messages, the captain had erroneously entered an airplane zero fuel weight (ZFW) that was 100,000 lbs. less than the actual ZFW when the first officer was out of the cockpit. After the captain made the incorrect ZFW entry, the flight crew did not perform another takeoff performance data briefing, and therefore did not recognize the captain's entry error that resulted in incorrect landing speeds calculated by the flight management software for the flight. During the approach, the flight crew did not notice indications that the target landing airspeed was too low, such as the Angle of Attack (AOA) indicator in the captains Heads Up Display (HUD) that was outside of the speed reference band, and the pitch of the airplane, which was about 7-8 degrees airplane nose up, whereas the normal airplane pitch on approach was 4-6 degrees pitch. The first officer also stated that during the approach he noticed that his airspeed indication had an amber box surrounding it, which is an indication that the airspeed had reached Vmin and was approaching a stall condition. During the flare and landing, the tail of the airplane struck the surface of the runway. The aircraft taxied normally to the cargo ramp, and an inspection revealed substantial damage to the skin, stringers, beams, APU compartment bulkhead, and aft pressure bulkhead of the airplane.

MCDONNELL DOUGLAS MD11FEDERAL EXPRESS CORP